As the development trend of modern remote sensing technology, image-spectrum associated detection is a great progress of remote sensing technology in the late period of the last century, also is the leading technology in the field of remote sensing. According to structure and characteristics of an electromagnetic spectrum, target infrared information refers to the difference of characteristics of radiation, reflection and scattering between a target acquired by an infrared band sensor and a background, which includes the characteristics of radiation, reflection and scattering in respective fine spectrum (light) bands of short wave infrared (SWIR), mid-wave infrared (MWIR), long-wave infrared (LWIR). The co-aperture broadband infrared optical system can simultaneously obtain the radiation energy of the SWIR, MWIR and LWIR, therefore there is a qualitative leap in improving detection precision and capability of detection and identification. With the rapid development of infrared photoelectric technology, the simultaneous detection on the radiation in a broadband range becomes very important, leading to an unprecedented growth of requirements on corresponding optical system and its design.
The co-aperture broadband infrared optical system is mainly characterized in: (1) “co-aperture” refers to that the LWIR imaging shares an aperture with the broadband infrared spectrum measurement, so that the target radiation can be fully utilized and meanwhile a high image-spectrum association precision can be achieved. (2) “Broadband” refers to that the range of system wave band is wide, which relates to short, medium and long waves, and the specific coverage is 2 μm-12 μm. However, because there are various limitations on infrared materials, processing ability, coating technology and the like in China, especially implementing broadband co-aperture in the case of not using special components or special materials while correcting various aberrations simultaneously, there is a huge challenge on design of the co-aperture broadband infrared optical system. Further, remote sensing infrared optical systems mostly work in a harsh environment temperature range, the thermal refractive index coefficient of the infrared optical material is large, and therefore, the environment temperature change may cause thermal defocusing of the infrared optical system and lead to degradation of image quality.
The infrared optical lens disclosed in the prior art is dual-band (medium wave and long wave), and is essentially assembled by 2 lenses: a mid-wave one and a long wave one; thereby having large volume and weight, and belonging to the coverage of a regular band.